Pavement and road markings and devices are fixed onto roads, pathways, runways and service areas for a variety of reasons. For example, raised pavement markings (RPMs), raised reflective pavement markings (RRPMs) and other tactile markings are often used to guide and warn road users or delineate reserved areas.
RRPMs are advantageous in that they assist warn and guide road users with audible and steering vibration feedback to the driver and they function in inclement weather for example when a roadway is heavily sheeted in water or fog.
Bituminous road surfaces are made from composite materials containing rock and emulsion. Road devices are often anchored in place using bitumen-based adhesives or bonding agents, which have the same properties as the emulsion used in the road surface. To install the device, a block of adhesive, or pre-formed adhesive pad, is firstly heated and then applied onto the road surface. The device is then placed onto the adhesive while still hot and optionally rotated and/or moved until the device is in the correct orientation and position. The adhesive is then left to cool and set hard to anchor the device in place.
The connection between the device and the road surface can become weak or vulnerable to breakage over time, particularly when the road and device have been exposed to repeated fluctuations in temperature. Bitumen expands and softens in warm temperatures and contracts and hardens in cold temperatures. Changes in ambient temperature, therefore, lead to tension in the road surface and in the adhesive medium connecting the devices to the road surface. Road devices do not expand or contract with the road surface to which they are connected to accommodate such changes.
The difference between the surface tensions in an inflexible solid-state road device, the flexible adhesive pad and the as constructed bitumous road surface is, therefore, constantly changing. Prolonged exposure to temperature fluctuations as a result of daily and climatic weather changes eventually leads to breakage of the connection between the device and the surface causing the device to disconnect from the surface. Impacts and wear caused by wheels of traffic exacerbates the weakening of the connection. Road devices that separate, come loose and break away from their mountings can be hazardous, particularly in heavy and fast-flowing traffic conditions. Devices can become airborne causing damage to property and personal injury and, in extreme cases, can have fatal consequences.
Great improvements have been made in the manufacture of RRPMs over time such as their Impact strength, ultraviolet protection and reflective properties. RRPMs are commonly manufactured from glass, aluminium or specially formed hardened plastics or polymers and are therefore inflexible. The connection of RRPMs to their adhesive pad and the roadway surface has not evolved nor has it been improved in accordance with road traffic safety or RRPM manufacture. RRPMs are inflexible and they are installed onto a flexible adhesive pad and this connection releases under climatic and road traffic forces.
The associated costs in the replacement maintenance and reinstatement of safety delineators due to their adhesive failure rate is a significant problem in the global road marking industry.
A need therefore exists for improved solutions for adhering pavement markers to pavement or roadway surfaces.